Specimens of fresh, brackish, and ocean waters have been collected along the gulf coast from Louisiana to western Florida, and along the Atlantic coast from New York to central Florida. Except for the bay between New York and New Jersey, mycobacteria have only rarely been found above the 39th parallel. Mycobacteria are present in higher concentrations in water of less than 1.5 percent salinity. Although not all specimens have been identified, most of the mycobacteria isolated can be placed in the Mycobacterium avium-intracellular-scrofulaceum complex.